Various kinds of electronic information products, such as computers, are now widely adopted and applied in different commercial and industrial fields. To meet consumers' demands, electronic information products have been designed to have high operating speed and increased access capacity. However, components in the electronic information products would produce a high amount of heat when they operate at high speed.
For example, among others, the central processing unit (CPU) of a computer produces the largest part of heat in the computer. When the heat produced by the CPU gradually increases, the computer would have reduced performance. And, when the produced heat has accumulated in the computer to exceed an allowable limit, the computer is subject to the danger of shutdown or even becoming seriously damaged. Moreover, to solve the problem of electromagnetic radiation, a case is usually used to enclose all the important computer components or elements therein. Therefore, it is a very important matter to quickly dissipate the heat produced by the CPU and other heat-producing elements in the computer case.
A common way to dissipate the heat produced by the CPU is to mount a heat sink atop the CPU. The heat sink has a first side formed with a plurality of radiating fins. An opposite second side of the heat sink without the radiating fins is indirect contact with the CPU, so that heat produced by the CPU is absorbed by the heat sink at the second side contacting with the CPU and then transferred to the radiating fins at the first side and finally radiated from the radiating fins into ambient air. Or, a cooling fan can be additionally mounted to produce airflows to carry away hot air around the CPU and the heat sink, so as to achieve the purpose of quick heat dissipation. The radiating fins must be fixedly located on the heat sink to space from one another.
FIGS. 1 and 1A are exploded and assembled perspective views, respectively, of a conventional heat sink unit 1, which includes a plurality of stacked radiating fins 11, at least one heat pipe 111 extended through the radiating fins 11, a tightening body 12 fitted around the stacked radiating fins 11, and a binder 13 fixedly bound around the stacked radiating fins 11. The tightening body 12 is provided at each of two ends with a hook member 121 for hooking to an insertion seat (not shown). A control lever 122 is connected to one of the hook members 121. The fixed binder 13 is in contact with a lower side of the tightening body 12. A user can operate the control lever 122 to apply a downward pressure on the tightening body 12, bringing the tightening body 12 to downward press against the fixed binder 13. In the conventional heat sink unit 1, the pressure from the tightening body 12 is applied on the binder 13 via one single point, and the binder 13 provides a relatively small pressure receiving area while no other supporting means are provided below the binder 13 to support the same. As a result, stress is concentrated on the fixed binder 13 and could not be dispersed, which causes deformation of the radiating fins 11 being bound together by the fixed binder 13. Moreover, when the number of the radiating fins 11 of the heat sink unit 1 is increased, the binder 13 actually fails to effectively bind the radiating fins 11 for them to maintain at fixed position relative to one another. Therefore, the heat sink unit 1 with unstably located radiating fins 11 has poor heat dissipating efficiency. In brief, the conventional heat sink unit 1 has the following disadvantages: (1) the stress tends to concentrate on some of the radiating fins of the heat sink unit; (2) the stress could not be uniformly dispersed; (3) the radiating fins are subject to deformation; and (4) the heat sink unit is adversely affected to have low heat dissipating efficiency.
It is therefore tried by the inventor to develop an improved stress equalized heat sink unit to overcome the drawbacks in the conventional heat sink unit.